1. Field of the Invention
This invention relates to methods and apparatus for detecting and locating the presence of liquids.
2. Introduction to the Invention
A number of methods have been used (or proposed for use) to detect a liquid leak. Many of these methods make use of two detector members which are insulated from each other in the absence of the liquid but which become electrically connected when the liquid is present. When the liquid to be detected is water or another electrolyte, the detector members may be wires which are continuously or intermittently exposed, so that when an electrolyte is present, the detector members are electrically connected to each other through the electrolyte--see for example U.S. Pat. No. 3,098,116 (Jore et al), especially FIGS. 2 and 3, and U.S. Pat. No. 4,319,232 (Westphal et al), especially FIGS. 2, 3, and 4. When the liquid to be detected is a hydrocarbon, the sensor may comprise a member which swells when it is contacted by the hydrocarbon and which thus causes the detector members to become electrically connected--see for example U.S. Pat. No. 3,470,340 (Hakka). Some of the known methods make use of elongate sensors which not only signal when the leak takes place, but also indicate the location of the leak. For this purpose, the sensor may include a third, fully insulated wire which can form part of an electrical bridge circuit including the leak connection--see for example U.S. Pat. No. 3,365,661 (Zimmerman), especially FIGS. 2 and 3.